Angewandte
Chemie
Sasaki, K. Omata, C. Kabuto, K. Kabuto, Y. Takeuchi, Tetrahe-
dron: Asymmetry 2004, 15, 555; d) (S)- and (R)-CFTA-Cl are
both commercially available from Kanto Denka Kogyo Co., Ltd.
9] T. Takahashi, A. Fukushima, Y. Tanaka, Y. Takeuchi, K. Kabuto,
C. Kabuto, Chem. Commun. 2000, 787.
[
[
[
10] Y. Takeuchi, H. Fujisawa, R. Noyori, Org. Lett. 2004, 6, 4607.
11] The Dd values are defined as d Àd , in which d and d are the
S
R
S
R
chemical shifts of the corresponding protons in the (S)- and (R)-
CFTA amides, respectively.
[
12] a) S. K. Latypov, J. M. Seco, E. Quiæoµ, R. Riguera, J. Org.
Chem. 1995, 60, 1538; b) C. R. S. Briggs, D. OꢀHagan, J. A. K.
Howard, D. S. Yufit, J. Fluorine Chem. 2003, 119, 9.
[
13] S. N. Lodwig, C. J. Unkefer, J. Labelled Compd. Radiopharm.
1998, XLI, 983; see also the Supporting Information.
[
14] CCDC-291185 and CCDC-291186 contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Scheme 2. Conformations of (S)- and (R)-CFTA amides of chiral
primary amines R R CHNH .
S
R
2
[
8a]
amide of 1-phenylethylamine
and ab initio calculations
(
GAUSSIAN98, RHF/6-31 + G*) of the CFPA amide of Val-
[
8b]
OMe as a similar molecule.
In summary, we have presented the CFTA method as a
new and reliable procedure for the determination of the
absolute configuration of chiral amines. This method has
important advantages over other conceptually similar proce-
dures available because of the very high reactivity of the
[
6]
agent and because the CÀF bond at the stereocenter exerts
[
12b]
strong conformational control on the amides.
For these
reasons we feel this method should be widely applicable.
Received: January 14, 2006
Published online: June 21, 2006
Keywords: CFTA diastereomers · configuration determination ·
.
NMR spectroscopy · reactivity
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[
7] The assignment of the AB-quartet-like proton signals for the p-
Tol group is much easier than that of the complex multiplet
signals for the Ph group, especially for those chiral amines with
aromatic residues.
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Angew. Chem. Int. Ed. 2006, 45, 4617 –4619
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